The invention resides in a two-part dental implant with an implant abutment and an implant body.
In dental medicine, the loss of a tooth is more and more often compensated for by dental implants. Also, for the replacement of other body parts, such as ears, eyes, or fingers, artificial parts can be adequately anchored in an elegant manner by modified dental implant systems.
The implant is inserted into a bone bearing structure, which is generated by surgical measures. If the implant is subjected during the healing phase to no loads or only to small loads, it is very likely that an onkylotic jointure between the implant body and the adjacent bone structure is formed. For a complete osseointegration, a lower jaw implant requires about three months and an implant in the upper jaw or in other areas requires about five to six months.
In order to provide for this time interval a clinically load-free situation for the inserted implant, the implant consists preferably of two parts.
A dental implant can be divided into three areas: the enossal implant body, the region of penetration through the soft tissue and the intra-oral part for receiving the superstructure. Today, mostly rotation-symmetrical enossal implant bodies are used. The intra oral part of the implant has the greatest variability as far as shape and functions are concerned. Depending on the planned use of the implant post, the abutment may be shaped like a tooth prepared to receive a crown or like a support element on a vital tooth (head anchor, web, magnet attachment). For epithesis, mainly magnet attachments and bottom anchors are used.
With a two-step implantation procedure, the implant is adopted in a sub- or transepithelial manner. Only after the healing period is the post for the reception of the prosthesis, the so-called implant abutment, screwed onto the enossal implant body. The division of the implant into an enossal body and an implant abutment to be screwed onto the enossal body requires a two- or multiple part implant system. The connections between these two- or multiple part implant systems are of different designs, depending on the manufacturer. In all systems, however, there are inaccuracies between the joining surfaces of the enossal implant body and the implant abutment--which are caused by manufacturing tolerances--inspite of the relatively high torques applied to the connecting screws at the interface between the enossal implant bodies and the abutment.
The jointure gap is often found in the peri-implantal connective tissue sleeve. The peri-implantal soft tissue is, in contrast to the periodontal tissue, a scar tissue with bad blood circulation, which is formed on the highly polished surface of the implant or the super-construction. It generally reacts with respect to insufficient mouth hygiene, rough surfaces and projecting crown edges in a more sensitive way than the dento-gingival unit of the natural tooth. The causes and particularly ways of containing inflammations of this tissue--the so-called peri-implantal mucosities--are presently the subject of research. The peri-implantitis causes--analog to paradontitis--tissue resorptions, which lead to crater-like bone collapse around the implant and expose the enossal implant body to plaque deposits. This results in a progressive cirulus vitiosus, which rapidly leads to a loss of the implant.
In a gap between the enossal implant body and the abutment of a two part implant system, ideal growth conditions are generated for anaerobic pathogens. It is likely that these gaps have a negative influence on the state of the soft tissue sleeve and induce a peri-implantal mucositis or peri-implantitis. In animal experiments made recently infiltration in the area of the connection was histologically determined, inspite of strict plaque control and clinically inflammation-free soft tissue.
Even with a precise extra-oral fitting of the abutment, no bacteria-tight jointures can be achieved as the newest research results show.
In addition, substantial problems occur with two-part implant system when the abutment loosens, which happens quite frequently. The extremely high number of load changes on the implant during chewing and swallowing causes the connecting screw to come lose. Particularly with firmly cemented restorations, the prosthesis superstructure must be made and installed new after it has become lose which is costly and time consuming.
There are no types of implants available which hold the screw safely in place. Even the use of a screw with a relatively large conical screw head, which is screwed into a form-fitting female structure in the enossal implant body, has not been found, in clinical use, to eliminate the problem or even significantly reduce the chance of the abutment to become lose. The efforts of the implant manufacturers to optimize the tightness of their two-part implant systems usually culminate in the provision of a silicon ring in the gap between the two parts. Such silicon rings however have insufficient resistance to the environment to which they are exposed in the mouth, which leads to substantial servicing requirements for the implant patient. Because of these important clinical disadvantages of silicon, the clinical use is really very questionable inspite of the fact that it has been shown that a better seal can be provided with the use of silicon rings.
It is the object of the invention to provide a two-part implant without the problems by which present implants are afflicted. The implant abutment should have a germ-tight connection to the enossal implant body and a loosening of the mounting screw during the life of the implant should not be possible.